Effects of intermittent normobaric hypoxia on substrate utilization and metabolic rate in sedentary males

Workman, Chad (2013) Effects of intermittent normobaric hypoxia on substrate utilization and metabolic rate in sedentary males. Masters thesis, Memorial University of Newfoundland.

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Abstract

The purpose of this study was to determine the effects of intermittent normobaric hypoxia on resting metabolic rate and substrate preference in sedentary males. After a 12-hour fast, 11 sedentary male subjects (acute) were individually exposed to 3 hours of intermittent normobaric hypoxia, achieving an isometabolic stress of ~80% oxygen saturation. A subset of 6 subjects (short term) continued with the hypoxia exposure for a further 6 sessions. Resting metabolic data was acquired immediately before and after the hypoxic exposure on day 1 for the acute exposure group and on days 1 and 7 for the short-term exposure group. Heart rate, blood pressure, oxygen saturation and Acute Mountain Sickness Score were monitored and recorded. In the acute exposure group, there was a significant increase in oxygen consumption, from 315 ml·min (±10) to 371 ml·min (±10). As well, there was a significant reduction of the respiratory exchange ratio, from 0.89 (±0.1) to 0.76 (±0.06). There was also a significant increase in oxygen consumption in the short-term exposure group, from 322 ml·min (±10) on pre-exposure day 1, to 3 7 6 ml·min (±7) post exposure on day 7 and a significant reduction in respiratory exchange ratio from 0.86 (±0.09) on preexposure day 1 to 0.73 (±0.05) post exposure day 7. These results demonstrate that intermittent normobaric hypoxia, as described here, is sufficient to induce an increase in resting metabolic rate resulting in a switch from primarily carbohydrate to primarily lipid substrate as the main energy source.

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